Igniter squib



R. E. BETTS IGNITER SQUIB FIG. 2

Filed Aug. 31. 1960 Aug. 13,1963

5 wu- F Robert E. Betfs,

INVENTOR.

BY 4 M- FIG.3

ted States The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to an igniter squib. Such a device is useful in the initiation of burning of solid propellants, and in igniting explosives.

Igniter squibs are being used extensively in ordnance devices, for igniting rocket motors, for activation of pressure vessels and for closing switches, where stray radiation is present. These squibs are generally provided with a safety feature so that energy delivered to the Wire at a level and rate which is under the conditions required for activation of the squids will not fire the squibs.

This invention provides a resistance wire removed from the igniter material, means for shielding the igniter material and means for permitting high voltages to are between the squib body and either lead Wire without danger to components used external to the squib. These features allow the squib to be used without danger from stray radiation. i

In view of these facts, an object of this. invention is to provide an igniter squib suitable for use, where stray radiation is present, without danger of being ignited from stray signals being radiated in the proximity of the squib.

Another object is to provide a squib with the pyrotechnic material shieldedjfrom the resistance wire.

A further object is to provide an igniter squib with;

means for removing the pyrotechnic material from the squib for purposes of storage or changing the size of FIGURE 2 is a partial sectional View showing the.

dielectric material in position.

FIGURE 3 is an elevational sectional view of another embodiment of the invention.

In the drawing, wherein for the purpose of illustration there is shown the invention, the numeral 1 designates an igniter squib having its elements partially contained in a housing 2 which can be of a material such as aluminum. t

The housing is open at one end; and this end is adapted atent' ice of end 7, of plug 3. These wires can be molded in the plug at the time of manufacture, or placed in apertures 4 as described above. These wires are joined byv a resistant containing bridge wire12 that extends along the source to the bridge wire.

face of end 7 and connects to wires 10. The other ends of wires 10 are covered by suitable insulating material 14 which extends into cavities 5. This material can also be molded in the plug during manufacture of the plug. t

The closed end of housing 2 encloses an electrical insulating cup 16, a metal shield 18, pyrotechnic material 20 contained in said shield and a spacer 22 for insuring that shield' l8 remains spaced from bridge wire 12. The metal shield 18 completely encloses the pyrotechnic material 20 and acts in the same manner as a Faraday shield which prevents static charges from passing through the pyrotechnic material 20 or building up on the surface of said material. Therefore this eliminates one of the possibilities of accidentally firing the pyrotechnic material. 'With these elements in position the open end of cup 16 is attached to plug 3 by a dielectric adhesive 24. When the cup is attached to plug 3 a cavity is formed, inside spacer 22 between shield 18 and end 7 of plug 3. .This cavity can be filled with a dielectric material 2-6 such as epoxy resin, preferably when a vacuum is formed in the cavity, or filled with air which serves as a dielectric.

The operation of this embodiment is as follows: The igniter squib is mounted in any known manner and the power for operating the squib and the control means (not shown) are connected to wires 10 With this arrangement, the squib is actuated by op eration of the control means which connects an electrical When the required electrical source reaches the bridge wire it is converted to heat, thereby developing pressure in the ;wire and cavity. This action causes the bridge wire to explode. The combination of the heat and the. explosion of the bridge wire ruptures the metal shield and ignites the pyrotechnic igniter material inside the shield.

As the igniter material burns it creates heat and pressure within the squib, thereby causing the closed end of the housing to rupture. When the housing ruptures hot gases and burning particles are forced into contact with to receive a phenolic bridge plug 3. This plug is provided with a pair of apertures 4 which connect with a pair of cavities 5 and a pair of arc gaps 6. Each gap is normal to and joins one of the apertures 4. One end 7 of the plug is reduced. so as to provide a space between this end and housing 2. The other end "8 of the plug has a smaller reduction, than the first-named end, which shifts into an angled portion 9. The smaller reduction serves as a support for housing 2, which is crimped in position along the reduction when the squib is as sembled.

surrounding material.

The operation of the arc gaps serves as a safety device by allowing electrostatic charges to be discharged between wires 10 and housing 2 without danger to either the ignition material or the external components surrounding the case.

In the embodiment shown in FIGURE 3, components common to both embodiments have the same reference numeral.

This embodiment discloses an igniter squib that allows the housing to be separated into two sections 28 and 6029. Section .28 contains the pyrotechnic material 20,

which is shielded by the Walls of section 28 and end plates 30 and 31. This section is provided with screwthreads 32 which serve to mount the section to another member and internal screwthreads 33 for coacting with screwthreads 34 of section 2.9 for connecting the sections together.

Section 29 is provided with an insulating bridge plug 36 and an insulating seal 37, of a suitable material such as ceramic. The plug and seal are apertured and wires 10 are maintained in the apertures as discussed in the first embodiment The portion of section 29 adjacent to said apertures is provided with apair of arc gaps 3-8 which allow wires 10 to pass thru the section. The regaps'is accomplishedbetween section Y29 and wires 10,

instead of.between the wires and a case.

It is tobe understood that the form of the invention thatfis herein shown and described is the preferred embodiment, and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention, or the scope of the subjoined claims.

The following invention is claimed:

1; An igniter squib comprising: a housing; a pyrotechnic material disposed in said housing; a sealed metal containencompletely enclosing said pyrotechnic material for shielding said material from static charges; a bridge plug partially enclosed by said housing and spaced from said metal container;.a non-explosive. dielectric between said plugand said metal container; a firing circuit disposed Within said housing and extending outwardly thereof through said bridge plug, said firing circuit provided with a bridge Wiredisposed in .saiddielectric; means for permitting the discharge of static electricity, between said firing circuit and saidhousing, inside said housing without danger of igniting said pyrotechnic material.

HZKA .device as set forth in claim 1, in which said housing 'iscomprised of metallic conducting material and has an open end and a closedend.

3. A device as set forth in claim 1, in which said 7 plug is comprised of a dielectric material.

4. A device as set forth in claim 1, in which said firingcircuit includes a pair of wires, passing thru said plug'and connected to said bridge wire and dielectric material separating said pairof wires.

' 5. A device as set forth in claim 1, in'which said means for permitting discharge of staticelectricity comprises an arc gap between the firing circuit and housing.

.6..An igniter squib comprising? a housing; a cupshaped member enclosed Within said housing; a sealed metal container retained in said member; a pyrotechnic material enclosed in said metal container; a bridge plug having one end positioned in the open endof said cupshaped member and the otherend extending from said housing; a firingcircuit in' contiguous relation with said plug, said firingcircuit having a bridge wire, and a pair of conductors having one end connected to said bridge wire and the other end extending thru said bridge plug, said "bridge. wire being disposed within said housing; means for permitting discharge of static electricity; between said firing circuit and said housing, inside said housing without danger of igniting said pyrotechnic material; means for connecting said member to said plug; a ring-shaped spacer positioned between, said metal container and plug; to define a space between said spacer, metal container, and plug; and a dielectric adjacent to said bridge wire enclosed by said spacer, metal container and plug. 7 V

7. A- device as set forth in claim 6, in which said member is comprised of a dielectric material.

8. A device as set forth in claim 6, in which one end of said bridge plug has a reduced portion extending into an'open end of said cup-shaped member, and a second reduced end having a portion engaging said housing for support of saidhousing.

9. A device as set-forth in claim 6, in which said a dielectric-material consisting of resin.

10. An igniter squib comprising: a housing of metallic conducting material; a cup-shaped member enclosed within said'housing; a sealed metal container retained insaid cup-shaped member; a pyrotechnic material enclosed by saidmetal container; a dielectric bridge plug having one end positioned in the open end of said cup-shaped member and the other end extending from said housing; a bridge wire positioned within said housing adjacent to one end of said plug; a pair of wires extending 'thnu said plug and'connected to said bridge wire, said bridge wire and pair of wires comprising, a firing circuit; means, positioned between-said pair of wires and said housing for permitting the discharge of static electricity inside said housing withoutdanger of igniting said pyrotechnic material; means for connecting said cup-shaped member to said plug; a ring-shaped spacer positioned between said metal container and said plug; and a'dielectric enclosed by said spacer, metal container and plug.

References Cited in the file ofthis patent UNITED STATES PATENTS 

1. AN IGNITER SQUIB COMPRISING: A HOUSING; A PYROTECHNIC MATERIAL DISPOSED IN SAID HOUSING; A SEALED METAL CONTAINER COMPLETELY ENCLOSING SAID PYROTECHNIC MATERIAL FOR SHIELDING SAID MATERIAL FROM STATIC CHARGES; A BRIDGE PLUG PARTIALLY ENCLOSED BY SAID HOUSING AND SPACED FROM SAID METAL CONTAINER; A NON-EXPLOSIVE DIELECTRIC BETWEEN SAID PLUG AND SAID METAL CONTAINER; A FIRING CIRCUIT DISPOSED WITHIN SAID HOUSING AND EXTENDING OUTWARDLY THEREOF THROUGH SAID BRIDGE PLUG, SAID FIRING CIRCUIT PROVIDED WITH A BRIDGE WIRE DISPOSED IN SAID DIELECTRIC; MEANS FOR PERMITTING THE DISCHARGE OF STATIC ELECTRICITY, BETWEEN SAID FIRING CIRCUIT AND SAID HOUSING, INSIDE SAID HOUSING WITHOUT DANGER OF IGNITING SAID PYROTECHNIC MATERIAL. 